Various types of cooled rollers are known, and the present invention is particularly directed to a double-walled cooling roller which has a cooling medium applied thereto concentric with the axis of rotation of the roller. German Utility Model No. 72 09 772 describes a double-walled cooling roller with centrally arranged cooling medium circuit connections positioned at one axial end thereof. The space between an inner and an outer jacket of the roller forms a flow chamber. This double-walled cooling roller has a drain connection at one axial end thereof which is adjacent the supply connection thereto.
The cooling medium is pumped in the space between the inner and outer jacket of the roller. This requires comparatively high pumping pressure. The high pumping pressure results, in part, due to the centrifugal force which is applied to the cooling medium upon rotation of the roller which is counter the direction of flow to a central supply or removal duct. The high pressure causes problems in connection with sealing of the cooling fluid. At high rotary speeds, a ring of cooling fluid, typically water, will result which interferes with efficient axial flow of the cooling water, and hence proper flow of the cooling medium throughout the space adjacent the outer jacket of the cooling roller.
It has previously been proposed to provide a separate motor driven fluid distribution drive or pump in flow connection with the cooling fluid in order to improve the flow relationships in the interior of the double-walled cooling roller. Such arrangements cause additional expense and, as has been found, are subject to malfunction.